Starting gear for internal combustion engines



Jan. 2, 1934. O A. c. LOC-K 1,941,698

STARTING GEAR FOR INTERNAL COMBUSTION ENGINES Filed July 21, 1932 2 SheetS -Sheet l Jan. 2, 1934. I A. Q K 1,941,698

STARTING GEAR FOR INTERNAL COMBUSTION ENGINES Filed July 21, 1932 2 Sheets-Sheet 2 m 34 I mun 45 T 3 44 50 36 v w 1 n um mm a, 3 9 mm m J\\\\\\\(,

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1 O x 0 Xvi-J 4 2e Q0 I 1 n W O 46 Patented Jan. 2, 1934 UNITED STATES STARTING GEAR FOR INTERNAL COMBUSTION ENGINES Archibald Charles Lock, Dulwich, England, as-

signor to Simms Motor Units Limited, London,

England Application July 21, 1932, Serial No. 623,882, and in Great Britain June 13, 1932 7 Claims.

This invention is for improvements in or relating to starting gear for internal combustion engines and of the type which comprises an electric motor having a toothed driving member (for example, a spur wheel) arranged, for the purpose of starting the engine, to be coupled to a toothed driven member (for example, a toothed ring or gear wheel provided upon or formed integrally with the engine fly wheel) and nori mally de-coupled, means being provided whereby the toothed driving member is automatically coupled to the driven member upon the starting of the motor and automatically de-coupled upon deceleration or stopping of the motor.

With starting gear of the above type the automatic coupling of the driving member to the driven member has usually been obtained by mounting the driving spur wheel upon the motor spindle and operatively connecting the same jthereto by means of a helical thread device which, when the motor commences to rotate, causes the spur wheel to be moved axially of the motor spindle so as to couple the spur wheel to the toothed ring on the fly wheel of the engine by lvirtue of the relative rotational movement be tween the motor spindle and the spur wheel due to the inertia of the spur wheel. Owing to the relatively rapid acceleration of the driving motor the spur wheel is moved into engagement Zwith the toothed ring with great force, resulting in destructive shocks being administered to the toothed ring (the spur wheel being usually hardened) and as a consequence, the teeth of the ring are rapidly destroyed.

The invention provides an improved form of starting gear of the type referred to wherein a movable toothed coupling element of the starter is provided together with means for imparting a coupling movement thereto, for example an axial movement, and is operatively associated with a switch device and a resistance element so that upon an initial actuation of the switch a circuit for the motor is closed through the resistance and the toothed driving member causes the switch device to short circuit the resistance when the coupling movement has been effected.

Means are preferably provided for positively retarding the rotation of the toothed drivingmember until the axial movement thereof has been effected and the coupling engagement of the said member with the driven member accom plished.

Thus, the invention provides a starting gear whereby the engagement of the toothed driving member with the driven member is effected when the driving member is running at a slow speed and no injury can thus be effected to the said members. The invention is more particularly described in the ensuing description and is defined in the appended claims.

In order that the invention may be fully understood, reference is directed to the accompanying drawings, in which:-

Figure l is a longitudinal sectional elevation of a starting gear constructed in accordance with this invention,

Figure 2 is a vertical section of a portion of the gear illustrated in Figure l,

Figure 3 is an underside View of Figure 2, and

Figure 4 is a section illustrating details on the line 4-4 of Figure 3. 1

Referring to the drawings, an electric driving motor of the starting gear is illustrated at 1, the spindle 2 of which is provided with an extension 3, the forward end of which is mounted in a bearing 4 provided in a frame structure 5 which is bolted to the motor 1. Upon the spindle extension 3 a spur wheel 6 is mounted and is operatively coupled therewith by means of a helical thread device such, for example, as that indicated in dotted lines at '7, Figure 1. These parts are of similar construction to those of known starting gears in which the operation is such that upon starting of the motor 1 with comparatively rapid acceleration, the inertia of the spur wheel 6 causes the same to be moved by virtue of the helical thread device 7 in the direction of the arrow or so as to be moved into coupling engagement with a toothed ring 8 provided upon the flywheel of an internal combustion engine so that continued rotation of the motor rotates the flywheel and enables the engine to be started. The leading edges of the teethof the spur wheel 6 are chamfered as indicated at 9 for the purpose of facilitating the engagement of the spur wheel with the toothed ring 8, it being appreciated that at the moment when the spur wheel moves axially towards the toothed ring 8, it is a matter of chance as to whether or not the teeth of the two members are in the correct positions relatively to oneanother to enable meshing between them to be obtained.

In accordance with this particular embodiment of the invention, means are provided which will now be describedflior ensuring that the motor 1 starts at a relatively low speed until the spur wheel 6 has been moved into mesh with the toothed ring 8, whereafter the motor is permitted to rotate at normal speed for starting the engine.

The spur wheel 6 is provided with an enlarged collar 10 which is arranged to co-operate with a brake pad 11 carried by one arm of a double-armed lever 12 which is pivotally mounted at 13 to a bracket 14 provided upon the lower end of the casing 15 of a solenoid device hereinafter described. The casing 15 is bolted to a seating 16 provided therefor upon the frame structure 5. The double-armed lever 12 is maintained in the normal position indicated in the drawings, by means of a spring 17 which presses a heel 18 of the lever, Figure 4, against an abutment 19 on the bracket 14. The other end of the lever 12 is provided with a hook 20 arranged in the path of movement of a hooked pawl 21 which is pivotally mounted at 22 to a head 23 carried by an extension 24 of the core 25 of the solenoid device. The core 25 is slidably mounted within a tube 26 which is disposed within the winding 2'7 of the solenoid located in the upper portion of the casing 15. The pawl 21 is arranged under the influence of a spring 28 and its normal position is determined by an adjustable set screw 29 mounted in the head 23.

The extension 24 of the solenoid core is provided with an insulating sleeve 30 upon which is slidably mounted a carbon disc 31 located between a pair of insulating washers 32. A flanged collar 33 arranged around the insulating sleeve 30 constitutes a distance piece between the insulated carbon disc 31 and the solenoid core 25. A partition element 34 is mounted within the casing 15 and is provided upon one side with a boss 35 in which a recess 36 is formed in which the tube 26 for the solenoid core 25 is arranged to extend. The partition element 34 is provided with a shoulder 3'7 against which the core 25 is normally arranged to abut under the influence of a spring 38 arranged around the sleeve 33, the said spring abutting against the flange of the said sleeve at one end and at the other end against the partition element 34. A spring 39 is disposed around the insulation tube 30 upon the opposite side of the disc 31 to that of the spring 38 and is arranged to press an annular dished metal contact bridge 40 against a shoulder 41 provided by the head 23, the bridge 40 being insulated by a washer 42 from the said head. A pair of diametrically opposed arcuate carbon contacts 43, 44 are mounted within the casing 15 and are insulated therefrom by insulating members 45. The contacts 43, 44 are secured respectively to corresponding copper contacts 46, 4'7 which are insulated by the material 45 from the casing 15 and are connected respectively with insulated terminal posts 48, 49 mounted upon the casing 15. The terminal 49 is electrically connected by a plate 50 to one of a pair of terminal posts 51 which are mounted upon but insulated from the casing 15 and serve as terminals for the winding 2'7 of the solenoid.

The circuit through the armature winding of the motor 1 of the starting gear as above de scribed, is connected to a battery B through the terminals 48, 49 in series so that with the position of the parts as illustrated in the drawings, the circuit of the motor is broken, The circuit of the solenoid winding 27 is also connected with the battery with the interposition of a starting switch S, as shown.

The operation of the starting gear as above described, is as iollows:-

Upon closing of the starting switch S, the solenoid winding 27 is energized and draws the core 25 inwardly of the winding in the direction of the arrow b, Figure 2, until the carbon disc 31 bridges the carbon contacts 43 and 44 and thus closes the circuit of the motor 1 through the terminals 48, 49. The resistance of the disc 31 and contacts 43, 44, however, in the circuit of the motor causes the motor to rotate at a relatively slow speed. During the movement of the core 25 above referred to, the extension 24 moves therewith and the pawl 21 engages the hook 20 and causes the lever 12 to rock about its pivot 13 so that the brake pad 11 is pressed against the collar 10 on the spur wheel 6, thus resisting its rotation with the motor spindle and facilitating the axial movement of the spur wheel along the spindle extension 3 by virtue of the helical thread device '7, so that the spur wheel is moved into mesh with the toothed ring 8 on the fly wheel of the engine. It will be appreciated that the limitation of the movement of the pad 11 by the collar 10 also limits the movement of the core 25 of the solenoid and the extension 24, but it is arranged that the initial movement permitted to the core is sufiicient to enable the disc 31 to bridge the contacts 43, 44 whilst this distance is insufficient to enable the bridge 40 to establish electrical connection between the contacts 46 and 47. As soon as the collar 10 of the spur wheel 6 has moved axially along the spindle extension 3 a suilicient distance to bring the said collar clear of the brake pad 11 and in which position the spur wheel 6 is in mesh with the toothed ring 8, further movement of the pad 11 and, therefore, the solenoid is permitted and the bridge 40 is moved into engagement with the contacts 46; 4'7 and thus short-circuits the contacts 43, 44 so that full current is supplied to the motor 1 which immediately accelerates and enables the engine to be started. During the further movement of the solenoid as described, it will be appreciated that the extension 24 moves relatively to the disc 31 and causes a compression of the spring 39.

The continued movement of the core of the solenoid which brings the bridge 40 into engagement with the contacts 46, 47 produces a further movement of the lever 12 which is suificient to cause the pawl 21 to ride past the hook 20 which is immediately restored to its normal position by the spring 17. Upon opening the starting switch and de-energizing the solenoid, the spring 39 restores the core to the normal position during which movement the rounded nose of the pawl 21 rides over the similarly rounded nose of the hook 20, compressing the spring 28 which subsequently restores the pawl 21 to the normal position in which the heel of the pawl abuts against the set screw 29.

By the described operation, it will be readily understood that the engagement of the spur wheel 7 with the toothed ring 3 on the engine fly wheel is eiiected at a speed of the motor which is sufficiently slow to prevent any material dam age being done to either of the interengaging elements, whilst enabling the full power of the motor to be employed for starting purposes immediately such engagement has been effected.

It is to be understood that the contacts 43 and 44 and the disc 31 may be formed of any suitable electrical resistant material and may be supplemented by additional resistances, if necessary, to ensure that the motor rotates at the desired slow speed when the motor circuit is established through the contacts referred to.

It is to be understood that any other electromagnetically actuated mechanism may be employed in lieu of the solenoid mechanism described above and in such an arrangement the armature of the mechanism is operatively con-- nected to the switch mechanism such as the disc 31 and the bridge 40 for controlling the circuits of the starting motor in a similar manner to that above described.

What I claim and desire to secure by Letters Patent is:-

1. In a starting gear adapted for automatic coupling to and uncoupling from a toothed driven member of an internal combustion engine, the combination of an electric motor, a toothed coupling element operatively connected to said motor, means operable automatically as the motor starts'to impart a coupling movement to said element, a resistance element connected in series with a winding of said motor, a switch operatively connected in series with said winding and said resistance element, a second switch operable when closed to short-circuit said resistance element, an electro-magnetically actuated prime mover operatively connected to both said switches so that when energized said prime mover closes the first switch, and an operative connection between the prime mover and said toothed coupling element operable to cause the prime mover to close the second switch only after the said coupling movement of said element has been effected.

2. In a starting gear for an internal combustion engine, the combination of an electric motor, a spindle driven by said motor, a spur wheel mounted on said spindle and coupled in driving relationship therewith, means operable automatically as the motor starts to move said spur wheel axially on said spindle, a resistance element connected in series with a winding of said motor, a switch operatively connected in series with said winding and said resistance element, a second switch operable when closed to short-circuit said resistance element, an electromagnetically actuated prime mover operatively connected to both said switches so that when energized the said prime mover closes the first switch, and an operative connection between the prime mover and the spur wheel adapted to cause the prime mover to close the second switch only after said axial movement of the spur wheel has been effected.

3. In a starting gear for an internal combustion engine, the combination of an electric motor having an armature winding, 2. spindle driven by said motor, a spur wheel mounted on said spindle and coupled thereto by a helical thread device adapted to cause axial movement of said spur wheel along said spindle when the spindle is rotated relatively to the spur wheel, a braking device for said spur wheel, a resistance element connected in series with the armature winding of said motor, a switch operatively connected in series with said winding and said resistance element, a second switch operable when closed to short-circuit said resistance element and an operator actuated delayed action device operatively connected to both said switches and to said braking device, and operable automatically when actuated to close the first switch and actuate the braking device and to close the second switch only after said axial movement of the spur wheel has been effected and means operable automatically thereafter to release the braking device, for the purpose described.

4. In a starting gear for an internal combustion engine, the combination of an electric motor having an armature winding, a spindle driven by said motor, a spur wheel mounted on said spindle and coupled thereto, means operable automatically as the motor starts to move said spur wheel axially of said spindle, a brake pad operable to be applied against said spur wheel, a resistance element connected in series with the armature winding of said motor, a switch operatively connected in series with said winding and said resistance element, a second switch operable when closed to short-circuit said resistance element and a delayed action device operatively connected to both said switches and to said brake pad and operable automatically to close the first switch and apply the brake pad against the spur wheel and thereafter to close the second switch only after said spur wheel is moved axially clear of said brake pad for the purpose described.

5. In a starting gear for an internal combustion engine, the combination of an electric motor having an armature winding, a spindle driven by said motor, a spur wheel mounted on said spindle and coupled thereto, means operable automatically as the motor starts to move said spur wheel axially of said spindle, a braking device for said spur wheel, a resistance element connected in series with the armature winding of said motor, a switch operatively connected in series with said winding and said resistance element, a second switch operable when closed to short-circuit said resistance element, an electromagnetically actuated prime mover operatively connected to both said switches and to said braking device, so that when energized said prime mover closes the first switch and actuates said braking device and thereafter closes the second switch only after axial movement of the spur wheel has been eiiected, for the purpose described.

6. In a starting gear for an internal combustion engine, the combination of an electric motor having an armature winding, a spindle driven by said motor, a spur wheel mounted on said spindle and coupled thereto by a helical thread device which causes axial movement of said spur wheel along said spindle when the spindle is rotated relatively to the spur wheel, a brake pad operable to be applied against said spur wheel, a resistance element connected in series with the armature winding of said motor, a switch operatively connected in series with said winding and said resistance element, a second switch operable when closed to short-circuit said resistance element, an electro-magnetically actuated prime mover operatively connected to both said switches and to said brake pad so that when energized said prime mover closes the first switch and applies the brake pad against the spur wheel and thereafter closes the second switch only after the spur wheel has been moved axially clear of the brake pad, for the purpose described.

7. In a starting gear for an internal combustion engine, the combination of an electric motor and a circuit therefor including a source of current supply, a spindle driven by said motor, a spur wheel mounted on said spindle, means operable automatically as the motor starts to move said spur wheel axially of said spindle, a braking device for said spur wheel, control means for said circuit operable to supply a sub-normal current from said source to said motor until at least part of the said axial movement of the spur wheel has been efiected and thereafter operable automatically to supply the normal current from said source to the motor, and an operative connection between the said control means and the braking device to brake the spur wheel when said control means is effective to supply sub-normal current to the motor and to release the brake when said control means is effective to supply normal current to said motor.

ARCHIBALD CHARLES LOCK. 

